Troubleshooting of Local Area Networks (LANs) requires that the technician have considerable knowledge of how the network functions, including the protocols of the network. In addition, they must have detailed knowledge of each type of message sent over the network, and the implications of each particular type of message being sent. This problem is more severe if a technician must trouble shoot more than one type of LAN, thus they must become familiar with each different protocol.
Typical prior art troubleshooting tools intercept each message, called a frame, sent over a LAN, and decode this frame to provide a more readable, English-like, version of the frame. However, a typical LAN can send 4 to 16 million bits of information per second, so troubleshooting an error condition may require the user of the troubleshooting tool to scan through many screens of decoded frame information to determine a possible cause for the fault that occurred on the LAN. For example, to detect and isolate a broken wire on a Token-Ring network may require paging through hundreds of Token-Ring Medium Access Control (MAC) frames.
Although problems on a LAN can occur at any time, problems are often associated with well defined sequences of frames on the LAN. For example, a new station attempting to connect to the LAN must go through a sequence of 5 phases, each requiring sending and receiving many MAC frames. These phases are defined by the architecture of the Token-Ring LAN. An error can occur in any of the required MAC frames for any of the phases, preventing the station from inserting itself into the LAN. The only indication to a user of the network station will be a message indicating that the station was unable to complete the station insertion process.
Should an error occur during operation of the LAN, such as the broken wire described above, the stations start a "beaconing" process to attempt recovery of the LAN. This is a complex process involving many beacon MAC frames sent over a variable period of time, and includes the possibility of two different network stations disconnecting and then reconnecting to the LAN.
The "token claiming" process is an architecturally well defined method on the LAN for determining an "active monitor", which is the network station that keeps the network operating smoothly. Should an error occur during token claiming, many frames need to be analyzed to determine the cause of the error. Neighbor notification and Ring Purge are examples of other well defined processes within a Token-Ring LAN, each of which requires many MAC frames to be sent and received over the LAN.
It is thus apparent that there is a need in the art for an improved method or apparatus which analyzes the messages sent over a LAN to provide information about the cause of an error on the LAN. There is a further need in the art for such a method or apparatus that analyzes selected error conditions that occur on a Token-Ring LAN and provide information about the cause of the selected error conditions. The present invention meets these and other needs.